working memory model (WMM)

creators of WMM

• Baddeley and Hitch (1974)

WMM definition

• Baddeley and Hitch criticised the MSM as overly simplistic, particularly with regard to STM

• The WMM shows that STM can be sub-divided into distinct components and is not a unitary stores (as proposed by the MSM)

• The WMM explains memories related to working on tasks that require immediate memory formation

  • Thus, the WMM refers to the ‘here-and-now’ STM function of memory

4 components of WMM

• central executive (CE)

• phonological articulatory loop (PAL)

• visuo-spatial sketchpad (VSS)

• episodic buffer (EB)

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central executive definition

• The role of the CE is to focus attention on the most important tasks that need attending to in the current moment

• The CE coordinates the 3 other components of the WMM by allocating them to different tasks

  • Each of the 3 components: PAL, VSS and EB - are known as ‘slave systems’

• The CE has limited capacity and cannot store information

phonological articulatory loop definition

• The PAL slave system is responsible for coordinating auditory information

  • Coding in the PAL is acoustic

• The PL preserves the order in which acoustic information is processed

  • Auditory rehearsal can take place here in the PAL

• There are 2 divisions to the PAL:

  • The phonological stores - this component stores spoken words (the inner ear)

  • The articulatory processes - this component stores written words (the inner voice)

    • Words are repeated on loop as part of maintenance rehearsal (but aren’t passed onto the LTM)

  • The PAL has a limited capacity

visuo-spatial sketchpad definition

• VSS component of the WMM is the slave system responsible for storing visual and/or spatial information

• Information is temporarily stored in the VSS

• The VSS has limited capacity

• The VSS can further be divided into:

  • The visual cache - stores visual data

  • The inner scribe - stores the arrangement of objects within the visual field of view

• Logie (1995) split the VSS into 2:

• A visual cache, storing visual data

• An inner scribe, storing the layout of objects in the visual field

episodic buffer definition

• The EB was added to the WM in 2000

• The function of the EB is to receive information from the CE, PL and VSS and to integrate this information into chronologically-ordered ‘episodes’

  • The EB records information as episodes so that it is time-sequenced

• Information is stored temporarily by the EB

• The EB is separate from LTM, but it forms an important stage in long-term episodic learning

• The capacity of the EB is limited

dual task paradigms as evidence for WMM

• If two tasks are undertaken at the same time that require the phonological articulatory loop for one and the visuo-spatial sketchpad for the other, then both tasks could be processed simultaneously

• However, if two tasks were to require just one of the slave systems, they would not be able to be processed simultaneously

  • Either one task can be processed then the other or the tasks would be flicked between, with neither being processed efficiently or effectively

• The dual task paradigms tells us that the PAL and VSS systems are separate components

  • If they are not separate components, no 2 tasks in the dual task paradigms would be able to be processed at the same time

  • This also indicates that both components exist and should appear in the model

research for dual task paradigms - Robins et al. (1996)

• Asked chess player to select moves (a visual skill) while doing another task at the same time

• The second task either required the articulatory loop or the visuo-spatial sketchpad

• As predicted, the quality of the chess moves decreased when the second task required the VSS or the CE

strengths of WMM explanation

• The case study of KF (Shallice and Warrington, 1970) offers support for the WMM

  • KF suffered a brain injury after which his STM was severely impaired (he could only keep 2 items in his STM) and he had poor STM ability for auditory information but had no problems processing visual information

    • KF’s phonological loop was damaged but the visuo-spatial sketchpad was intact

    • However, when KF completed a digit span and read the digits to himself, he remembered more than 2 items - this evidences the idea that there is more than one ST store, which is a flaw of MSM

  • KF struggled to process verbal/auditory information but his ability to recall visual information was unaffected

  • This is evidence that there are different slave systems in the working memory which code for verbal/auditory information and visual information

• Dual-task performance effect (Baddeley, 1976) may provide evidence for the CE

  • Participants were asked to perform a digit span task (repeating a list of numbers) and a verbal reasoning task (answering true or false questions) at the same time

  • As the number of digits increased, participants took longer to answer the true/false questions (not significantly longer)

  • Baddeley concluded that verbal reasoning task used the CE and the digit span task used the PAL

• Dual task paradigms supports the WWM empirically

  • The dual task paradigms demonstrate that the PAL and VSS do exist and that they are separate from one another, improving the validity of the model

weaknesses of WMM explanation

• There is a lack of detail on the role of the CE

  • This lack of detail may be due to the fact that the CE is very difficult to operationalise and measure

  • There may be more than one central component to the CE but to date, this has not been established with empirical evidence, making it non-falsifiable

  • There is no evidence to show what effect of removing the CE from the model would have on memory, making it an unscientific component

• The dual-task performance effect relies highly on controlled lab conditioning, using tasks that are unrelated to real-life scenarios

  • This lowers the ecological validity of this empirical evidence

• The WWM doesn’t show how other sensory information, such as touch, taste and smell, can be processed in the STM